A COMPACT DUAL-BAND BANDSTOP FILTER USING A CIRCULAR, FOLDED, SYMMETRIC, MEANDERED-LINE, STEPPED-IMPEDANCE RESONATOR

摘要

This letter describes the implementation of a dual-band bandstop filter based on a circular, folded, symmetric-type, two-section, meandered-line, stepped-impedance resonator (SIR), resonating at f_1=3.17 GHz and f_2=8.50 GHz. The length of each section of meandered-line is equal to 0.30 and is 0.60 times the guided wavelength (λ_g), which can be properly tuned to control the first and second resonant frequencies. The attenuation level of the signal at 5.83 GHz can be increased by the proper placement of transmission zero, which ultimately helps to generate a controllable ultrawide stop band bandwidth. This filter reached an attenuation level of 32.75 and 26.21 dB with insertion losses of 0.43 and 0.39 dB at the respective stop bands. The size of the filter was drastically reduced using a simplified architecture as a circular, folded, meandered-line, SIR.